Process for Making Alkylated Aromatic Compound

ABSTRACT

A process for producing an alkylated aromatic compound comprises contacting an aromatic starting material and hydrogen with a plurality of catalyst particles under hydroalkylation conditions to produce an effluent comprising the alkylated aromatic compound, the catalyst comprising a composite of a solid acid, an inorganic oxide different from the solid acid and a hydrogenation metal, wherein the distribution of the hydrogenation metal in at least 60 wt % of the catalyst particles is such that the average concentration of the hydrogenation metal in the rim portion of a given catalyst particle is Crim, the average concentration of the hydrogenation metal in the outer portion of a given catalyst particle is Couter, the average concentration of the hydrogenation metal in the center portion of the given catalyst particle is Ccenter, where Crim/Ccenter≧2.0 and/or Couter/Ccenter 2.0. Also disclosed are rimmed catalyst and process for making phenol and/or cyclohexanone using the catalyst.

PRIORITY CLAIM TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 61/804,957 filed Mar. 25, 2013, and European Application No.13172273.8 filed Jun. 17, 2013, the disclosures of which are fullyincorporated herein by their reference.

FIELD

The present invention relates to processes for making alkylated aromaticcompounds by hydroalkylation. In particular, the present inventionrelates to processes for producing cyclohexylbenzene by hydroalkylatingbenzene in the presence of a catalyst. The present invention is useful,e.g., in producing phenol and cyclohexanone starting fromhydroalkylation of benzene.

BACKGROUND

Phenol is an important product in the chemical industry and is usefulin, for example, the production of phenolic resins, bisphenol A,ε-caprolactam, adipic acid, plasticizers, and polymers such as nylon-6.

Currently, a common route for the production of phenol is the Hockprocess via cumene. This is a three-step process in which the first stepinvolves alkylation of benzene with propylene in the presence of anacidic catalyst to produce cumene. The second step is oxidation,preferably aerobic oxidation, of cumene to the corresponding cumenehydroperoxide. The third step is the cleavage of the cumenehydroperoxide in the presence of heterogeneous or homogeneous catalystsinto equimolar amounts of phenol and acetone, a co-product. However, theworld demand for phenol is growing more rapidly than that for theacetone co-product. This imbalance depresses the value of the co-productreducing the economic benefits of the Hock process.

Thus, a process that coproduces higher ketones, rather than acetone, maybe an attractive alternative route to the production of phenol. Inaddition, there is a growing market for cyclohexanone, which is used asan industrial solvent, as an activator in oxidation reactions and in theproduction of adipic acid, cyclohexanone resins, cyclohexanone oxime,caprolactam, and nylon-6.

As it has been recently disclosed, phenol and cyclohexanone can beco-produced by a novel process in which cyclohexylbenzene is oxidized toobtain cyclohexylbenzene hydroperoxide, which, in turn, is decomposed inthe presence of an acid catalyst to the desired phenol and cyclohexanonein a cleavage process.

Although the production of phenol and cyclohexanone fromcyclohexylbenzene appears to be analogous to the Hock process forproducing phenol and acetone from cumene, the chemistries in each stepare actually very different.

It is known from U.S. Pat. Nos. 5,053,571 and 5,146,024 thatcyclohexylbenzene can be produced by contacting benzene with hydrogen inthe presence of a catalyst comprising ruthenium and nickel supported onzeolite beta and that the resultant cyclohexylbenzene can be processedin two steps to cyclohexanone and phenol. U.S. Pat. No. 6,037,513discloses that cyclohexylbenzene can be produced by contacting benzenewith hydrogen in the presence of a bifunctional catalyst comprising amolecular sieve of the MCM-22 family and at least one hydrogenationmetal selected from palladium, ruthenium, nickel, cobalt and mixturesthereof. The catalyst also contains a binder and/or matrix and in theExamples the catalyst is produced by impregnating an extrudate of theMCM-22 family molecular sieve and an alumina binder with an aqueoussolution of a salt of the hydrogenation metal using incipient wetnessimpregnation. The '513 patent also discloses that the resultantcyclohexylbenzene can be oxidized to the corresponding hydroperoxide andthe peroxide decomposed to the desired phenol and cyclohexanone.

SUMMARY

According to the present disclosure, a hydroalkylation catalyst formaking an alkylated aromatic compound such as cyclohexylbenzenecomprising a solid acid such as a molecular sieve, an inorganic oxidedifferent from the solid acid and a hydrogenation metal and exhibiting asignificantly higher concentration of the hydrogenation metal in the rimportion and/or outer portion compared to the center portion of thecatalyst particles demonstrated very high benzene conversion andcyclohexylbenzene and dicyclohexylbenzene selectivity. Given that suchrimmed hydrogenation metal distribution may require shorter diffusiontime of the reactant in the hydroalkylation reaction, this catalyst canhave better monoalkylation selectivity and improve the yield of thedesired cyclohexylbenzene product.

A first aspect of the present disclosure relates to a process forproducing an alkylated aromatic compound, the process comprisingcontacting an aromatic starting material and hydrogen with a pluralityof catalyst particles under hydroalkylation conditions to produce aneffluent comprising the alkylated aromatic compound, the catalystcomprising a composite of a solid acid, an inorganic oxide differentfrom the solid acid and a hydrogenation metal, wherein the distributionof the hydrogenation metal in at least 60 wt % of the catalyst particlesis such that:

the average concentration of the hydrogenation metal in the rim portionof a given catalyst particle is Crim;

the average concentration of the hydrogenation metal in the outerportion of a given catalyst particle is Couter; and

the average concentration of the hydrogenation metal in the centerportion of the given catalyst particle is Ccenter;

where at least one of the following conditions is met:

(i) Crim/Ccenter

2.0; and

(ii) Couter/Ccenter

2.0.

A second aspect of the present disclosure relates to a process formaking phenol and/or cyclohexanone, the process comprising:

(1) producing cyclohexylbenzene using a process according to the firstaspect;

(2) oxidizing at least a portion of the cyclohexylbenzene to producecyclohexylbenzene hydroperoxide; and

(3) cleaving at least a portion of the cyclohexylbenzene hydroperoxideto obtain phenol and cyclohexanone.

A third aspect of the present disclosure relates to a catalyst, thecatalyst comprising a composite of a solid acid, an inorganic oxidedifferent from the solid acid and a hydrogenation metal, wherein thedistribution of the hydrogenation metal in at least 60 wt % of thecatalyst particles is such that:

the average concentration of the hydrogenation metal in the rim portionof a given catalyst particle is Crim;

the average concentration of the hydrogenation metal in the outerportion of a given catalyst particle is Couter; and

the average concentration of the hydrogenation metal in the centerportion of the given catalyst particle is Ccenter;

where at least one of the following conditions is met:

(i) Crim/Ccenter

2.0; and

(ii) Couter/Ccenter

2.0.

Additional features and advantages of the invention will be set forth inthe detailed description and claims, as well as the appended drawings.It is to be understood that the foregoing general description and thefollowing detailed description are merely exemplary of the invention,and are intended to provide an overview or framework to understandingthe nature and character of the invention as it is claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the cross-section of a catalystparticle in one embodiment of the present disclosure.

FIGS. 2A and 2B are schematic illustrations of cross-sections ofcatalyst particles in additional embodiments of the present disclosure.

FIGS. 3A, 3B, and 3C are schematic illustrations of catalyst particlesand directions in which cross-sections may be taken.

FIGS. 4 and 5 are diagrams showing Pd concentration distributions inEMPA line-scans of cross-sections of Catalyst A and Catalyst B,respectively, described in the Examples in the present disclosure.

DETAILED DESCRIPTION

In the present disclosure, a process is described as comprising at leastone “step.” It should be understood that each step is an action oroperation that may be carried out once or multiple times in the process,in a continuous or discontinuous fashion. Unless specified to thecontrary or the context clearly indicates otherwise, each step in aprocess may be conducted sequentially in the order as listed, with orwithout overlapping with one or more other step, or in any other order,as the case may be. In addition, one or more, or even all steps, may beconducted simultaneously with regard to the same or different batch ofmaterial(s). For example, in a continuous process, while a first step ina process is being conducted with respect to a raw material just fedinto the beginning of the process, a second step may be carried outsimultaneously with respect to an intermediate material resulting fromtreating the raw materials fed into the process at an earlier time inthe first step.

Unless otherwise indicated, all numbers indicating quantities in thepresent disclosure are to be understood as being modified by the term“about” in all instances. It should also be understood that the precisenumerical values used in the specification and claims constitutespecific embodiments. Efforts have been made to ensure the accuracy ofthe data in the examples. However, it should be understood that anymeasured data inherently contains a certain level of error due to thelimitation of the technique and equipment used for making themeasurement.

As used herein, the indefinite article “a” or “an” shall mean “at leastone” unless specified to the contrary or the context clearly indicatesotherwise. Thus, embodiments using “a hydrogenation metal” includeembodiments where one, two, or more different types of the hydrogenationmetals are used, unless specified to the contrary or the context clearlyindicates that only one type of the hydrogenation metal is used.

As used herein, “wt %” means percentage by weight, “vol %” meanspercentage by volume, “mol %” means percentage by mole, “ppm” meansparts per million, and “ppm wt” and “wppm” are used interchangeably tomean parts per million on a weight basis. All “ppm” as used herein areppm by weight unless specified otherwise. All concentrations herein areexpressed on the basis of the total amount of the composition inquestion unless specified or indicated otherwise. All ranges expressedherein should include both end points as two specific embodiments unlessspecified or indicated to the contrary.

Nomenclature of elements and groups thereof used herein are pursuant tothe Periodic Table used by the International Union of Pure and AppliedChemistry after 1988. An example of the Periodic Table is shown in theinner page of the front cover of Advanced Inorganic Chemistry, 6^(th)Edition, by F. Albert Cotton et al. (John Wiley & Sons, Inc., 1999).

As used herein, the term “methylcyclopentanone” includes both isomers2-methylcyclopentanone (CAS Registry No. 1120-72-5) and3-methylcyclopentanone (CAS Registry No. 1757-42-2), at any proportionbetween them, unless it is clearly specified to mean only one of thesetwo isomers or the context clearly indicates that is the case. It shouldbe noted that under the conditions of the various steps of the presentprocesses, the two isomers may undergo isomerization reactions to resultin a ratio between them different from that in the raw materialsimmediately before being charged into a vessel such as a fractionationcolumn.

As used herein, the generic term “dicylcohexylbenzene” (“DiCHB”)includes, in the aggregate, 1,2-dicyclohexylbenzene,1,3-dicylohexylbenzene, and 1,4-dicyclohexylbenzene, unless clearlyspecified to mean only one or two thereof. The term cyclohexylbenzene,when used in the singular form, means mono substitutedcyclohexylbenzene. As used herein, the term “C12” means compounds having12 carbon atoms, and “C12+ components” means compounds having at least12 carbon atoms. Examples of C12+ components include, among others,cyclohexylbenzene, biphenyl, bicyclohexane, methylcyclopentylbenzene,1,2-biphenylbenzene, 1,3-biphenylbenzene, 1,4-biphenylbenzene,1,2,3-triphenylbenzene, 1,2,4-triphenylbenzene, 1,3,5-triphenylbenzene,and corresponding oxygenates such as alcohols, ketones, acids, andesters derived from these compounds. As used herein, the term “C18”means compounds having 18 carbon atoms, and the term “C18+ components”means compounds having at least 18 carbon atoms. Examples of C18+components include, among others, diicyclohexylbenzenes (“DiCHB,”described above), tricyclohexylbenzenes (“TriCHB,” including all isomersthereof, including 1,2,3-tricyclohexylbenzene,1,2,4-tricyclohexylbenzene, 1,3,5-tricyclohexylbenzene, and mixtures oftwo or more thereof at any proportion). As used herein, the term “C24”means compounds having 24 carbon atoms.

The term “MCM-22 type material” (or “material of the MCM-22 type” or“molecular sieve of the MCM-22 type” or “MCM-22 type zeolite”), as usedherein, includes one or more of:

-   -   molecular sieves made from a common first degree crystalline        building block unit cell, which unit cell has the MWW framework        topology. A unit cell is a spatial arrangement of atoms which if        tiled in three-dimensional space describes the crystal        structure. Such crystal structures are discussed in the “Atlas        of Zeolite Framework Types,” Fifth Edition, 2001, the entire        content of which is incorporated as reference;    -   molecular sieves made from a common second degree building        block, being a 2-dimensional tiling of such MWW framework        topology unit cells, forming a monolayer of one unit cell        thickness, desirably one c-unit cell thickness;    -   molecular sieves made from common second degree building blocks,        being layers of one or more than one unit cell thickness,        wherein the layer of more than one unit cell thickness is made        from stacking, packing, or binding at least two monolayers of        one unit cell thickness. The stacking of such second degree        building blocks can be in a regular fashion, an irregular        fashion, a random fashion, or any combination thereof; and    -   molecular sieves made by any regular or random 2-dimensional or        3-dimensional combination of unit cells having the MWW framework        topology.

Molecular sieves of the MCM-22 type include those molecular sieveshaving an X-ray diffraction pattern including d-spacing maxima at12.4±0.25, 6.9±0.15, 3.57±0.07, and 3.42±0.07 Angstrom. The X-raydiffraction data used to characterize the material are obtained bystandard techniques such as using the K-alpha doublet of copper asincident radiation and a diffractometer equipped with a scintillationcounter and associated computer as the collection system.

Materials of the MCM-22 type include MCM-22 (described in U.S. Pat. No.4,954,325), PSH-3 (described in U.S. Pat. No. 4,439,409), SSZ-25(described in U.S. Pat. No. 4,826,667), ERB-1 (described in EuropeanPatent No. 0293032), ITQ-1 (described in U.S. Pat. No. 6,077,498), ITQ-2(described in International Patent Publication No. WO97/17290), MCM-36(described in U.S. Pat. No. 5,250,277), MCM-49 (described in U.S. Pat.No. 5,236,575), MCM-56 (described in U.S. Pat. No. 5,362,697), andmixtures thereof. Other molecular sieves, such as UZM-8 (described inU.S. Pat. No. 6,756,030), may be used alone or together with the MCM-22type molecular sieves as well for the purpose of the present disclosure.Desirably, the molecular sieve used in the catalyst of the presentdisclosure is selected from (a) MCM-49; (b) MCM-56; and (c) isotypes ofMCM-49 and MCM-56, such as ITQ-2.

Hydroalkylation catalysts can be used in various reactors, such asfixed, ebullating, or fluidized bed, or slurry reactors. Fixed beds areoften preferred due to their lower cost operation and easier reactionmedium/catalyst separation. For fixed bed applications, practicalcatalysts are typically shaped into extrudates or pellets for ensuringlow flow resistance through the catalyst bed and for good contactbetween the catalyst and the reaction medium. The extrudates may haveround or other solid cross-sectional profiles, but they may even betubular. To increase the outside surface area and to reduce the averagediffusion path length of the reactants and products at a given overallcross sectional area of a rod-like solid extrudate, the shape of thecross section often has multiple lobes. For example, a quadralobeextrudate has four lobes, which can be considered as protrusions on around core.

The catalyst disclosed herein is in solid state under use conditions.The catalyst material in use may exhibit multiple or a single geometryand size. Thus, the catalyst may manifest itself as pellets, powders, ormonolithic bodies. For the convenience of description herein, thesedifferent solid manifestations are connectively called “particles,”regardless of their actual sizes, which may range from nanoscopic tomacroscopic scales. For the convenience of description, the term“particle” is also used interchangeably with the term “pellet” herein.For each particle or pellet, there is a hypothetical three-dimensionalrectangular cuboid capable of containing the particle having threedimensions a, b, and c, where a≧b≧c, with the smallest possible volume.The longest dimension of the rectangular cuboid, a, is called thelongest axis of the particle.

The cross-section of the catalyst particle is taken by intersecting theparticle by a plane perpendicular to its longest axis, a. For aspherical particle shown in FIG. 3A, the cross-section would be a circleperpendicular to any diameter thereof taken in the direction of AA′. Fora cylindrical particle having a height larger that its diameter, such asone illustrated in FIG. 3B, the cross-section can be taken in thedirection of BB′ and would be a circle having a radius of the cylinderperpendicular to the axis of the cylinder, shown in FIG. 2A. For a cubicparticle, the cross-section can be any of the planes that runs parallelwith one of the faces of the cube and runs through the center of thecube. Unisothropical shapes, often made by extrusion in the art ofcatalyst manufacturing, may have many types of cross-sections that couldbe, for example, round forming a cylinder, or lobed rectangles orcircles forming cylinders of increased surface area, etc. Most typicallythese catalyst particles have the characteristic of a “noodle-like”shape with a longest axis and various cross-sectional shapes that can betaken in the direction CC′, and a/b>1, where a and b are defined above,such as one illustrated in FIG. 3C. For the purpose of characterizingmetal distribution in the cross-section in the present disclosure, thecross-section of these catalyst particles, schematically illustrated inFIG. 2B, would be a cut perpendicular to its longest axis anywhere alongthat axis as long as the cut is made at a distance of at least 0.5×bfrom either end of the extrudate, where b is defined above. Thus, forexample, in the case of a round cross-section of an ideal cylindercatalyst particle, b would be equal to the diameter of thecross-section.

For a solid particle, the cross-section would be a continuous areabounded by an outer perimeter without an inner boundary. For a hollowparticle, the cross-section can be a continuous area defined by an outerboundary and at least one inner boundary.

Referring to FIG. 1, the definition of the center of a cross-section Ois given as follows.

Any given point (P) inside the area bounded by the outer perimeter 103of the cross-section 101 has distances of r₁, r₂, r₃, . . . , and r_(n),to the different points on the perimeter of the cross-section. Theaverage mean square distance is calculated as:

$r_{ms} = {\frac{\sqrt{r_{1}^{2} + r_{2}^{2} + r_{3}^{2} + \ldots + r_{n}^{2}}}{n}.}$

The center (O) of the cross-section is the point inside the outerperimeter having the smallest average mean square distance r_(ms) to theouter perimeter. For a centrally symmetrical cross-section, the centerwould be the center of symmetry, such as the center of a circle, anelliptical, a square, or a rectangle.

For any given point P inside the outer perimeter, draw a straight linepassing both points O and P. The line intersects the outer perimeter atpoints Q and Q′ such that P is located between Q and O. The length ofthe segment between points Q and O is |QO|, and the length of thesegment between points P and O is |PO|. Note that for all possiblechoices of P, i.e., for all points within the cross-section, |PQ|≦|QO|.Using these definitions, the rim portion, the outer portion, and thecenter portion of a cross-section can be given as follows:

The rim portion of the cross-section is defined as the area occupied byall possible points P for which |PQ|/|QO|≦0.20. For a circularcross-section having a radius r₀, the rim portion would be the ringbounded by the outer perimeter of the cross-section and a concentriccircle having a radius of 0.8·r₀.

The “outer portion” of the cross-section is defined as the area occupiedby all possible points for which |PQ|/|QO|≦0.30. For a circularcross-section having a radius r₀, the outer portion would be the ringbounded by the outer perimeter of the cross-section and a concentriccircle having a radius of 0.7·r₀.

The center portion of the cross-section is defined as the portionoccupied by all points P for which |PO|/|QO|≦0.10. Thus, the centerportion of the cross-section shares a common center O with the entirecross-section. For a circular cross-section having a radius r₀, thecenter portion would be a concentric circle having a radius of 0.1·r₀.In general, the center portion of the cross-section has the same orsimilar shape as the entire cross-section and can be enlarged to overlapwith the full cross-section without rotating it around its center.

For a given catalyst particle cross-section, the concentration of agiven metal, such as Pd, may be measured using known methods such a EPMAanalysis. The average concentration in the rim portion is Crim, and theaverage concentration in the center portion is Ccenter. As used herein,a “rimmed catalyst” is a catalyst exhibiting Crim/Ccenter>1.0, i.e.,that which exhibits a higher average concentration in the rim portionthan in the center portion.

Hydroalkylation converts aromatic hydrocarbons, such as benzene,substituted benzenes, such as toluene, ethylbenzene, cumene,cyclohexylbenzene, xylenes, etc., naphthalene, substituted naphthalenesand the like, and hydrogen to alkyl-aromatic compounds, in which thearomatic component of the feed is substituted by an alkyl componentderived by the partial hydrogenation of the same aromatic feedcomponent. An example of such process is the hydroalkylation of benzeneto cyclohexylbenzene (CHB).

The catalyst used in the present disclosure is characterized in thepreferential distribution of the hydrogenation metal in the rim portionand/or outer portion compared to the center portion of a majority of thecatalyst particles. The catalyst particles comprise a composite of asolid acid, an inorganic oxide different from the solid acid and ahydrogenation metal, and the distribution of the hydrogenation metal inat least 60 wt % (or at least aa wt %, where aa can be: 65, 70, 75, 80,85, 90, 95, 98, or even 99) of the catalyst particles is such that theaverage concentration of the hydrogenation metal in the rim portion of agiven catalyst particle is Crim, the average concentration of thehydrogenation metal in the outer portion of a given catalyst particle isCouter, the average concentration of the hydrogenation metal in thecenter portion of the given catalyst particle is Ccenter, whereCrim/Ccenter≧2.0 and/or Couter/Ccenter

2.0. In certain embodiments, at least one of the following conditions smet: (i) X

Crim/Ccenter

Y; and (ii) X

Couter/Ccenter

Y, where X can be: 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0,13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, 20.0, 25.0, 30.0, 35.0, 40.0,45.0, 50.0, 60.0, 70.0, 80.0, 90.0, or even 100.0; and Y can be: 50000,20000, 10000, 8000, 5000, 3000, 2000, 1000, 900, 800, 700, 600, 500,400, 300, 200, 180, 160, 150, 140, 130, 120, 110, 100, 90.0, 80.0, 70.0,60.0, or even 50.0, as long as X<Y.

The solid acid component in the composite of the catalyst of the presentdisclosure provides at least a portion of the alkylation function of thecatalyst. The solid acid can be, e.g., a molecular sieve, amorphoussilica-alumina, or mixed metal oxides such as tungstated zirconia, orother suitable solid acid known in the art. Suitable solid acidmolecular sieves include but are not limited to: mordenite, zeolite X,Y, beta, molecular sieves of the MWW type, such as those in the MCM-22type as described above. Examples of MWW type molecular sieves that canbe advantageously used in the catalyst of the present disclosure includebut are not limited to: MCM-22, PSH-3, SSZ-25, ERB-1, ITQ-1, ITQ-2,MCM-36, MCM-49, and MCM-56.

The inorganic oxide different from the molecular sieve contained in thecatalyst of the present disclosure can provide multiple functions suchas (i) binding the molecular sieve particles together to form a largerparticle such as a pellet or other monolithic body; (ii) supporting thehydrogenation metal in the catalyst particle; and (iii) optionallyproviding acidic locations capable of catalyzing the alkylationreactions. Thus, the inorganic oxide may comprise one or more of thefollowing: silica; alumina; zirconia; titania, and oxides of othermetals in Group 2, 3, 4, 5, 6, 7, 13, and 14 of the Periodic Table ofElements. The amount of the inorganic oxide different from the solidacid present in the catalyst particle may vary. For example, the weightratio of the solid acid to the inorganic oxide different from the solidacid can range from R1 to R2, where R1 can be 0.1, 0.2, 0.3, 0.4, 0.5,0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9,2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.5, 4.0, 4.5,5.0; and R2 can be 8.0, 7.5, 7.0, 6.5, 6.0, 5.5, 5.0, 4.9, 4.8, 4.7,4.6, 4.5, 4.4, 4.3, 4.2, 4.1, 4.0, 3.5, 3.0, 2.5, 2.0, as long as R1<R2.In one example, the weight ratio of the solid acid to the inorganicoxide different from the solid acid is about 4.0, which was found to beparticularly advantageous for a catalyst comprising a MWW type molecularsieve (the solid acid) and Al₂O₃ binder (the inorganic oxide differentfrom the solid acid).

The catalyst used in the process of the present disclosure may comprisea promoter, such as a metal selected from Groups 1, 2, 13 and 14 of thePeriodic Table of Elements, Zn, halogens, and the like.

The hydrogenation metal catalyzes the hydrogenation of at least a partof the feed material to produce an alkylating agent (e.g., an olefin)during the hydroalkylation process, which, in turn, reacts with part ofthe feed material to produce the desired alkylated aromatic compound.The hydrogenation metal is advantageously selected from Groups 8-10metals of the Periodic Table of Elements, and mixtures and combinationsthereof. Particularly advantageous hydrogenation metal is selected from:Fe, Co, Ni, Ru, Th, Pd, Os, Ir, Pt, Zr, and mixtures and combinationsthereof. The amount of the hydrogenation metal present in the catalystparticles can vary. For example, the weight percentage of thehydrogenation metal, expressed on the basis of metallic metal, relativeto the total weight of the catalyst particle, can be in the range fromA1% to A2%, where A1 can be 0.001, 0.005, 0.01, 0.05, 0.10, 0.15, 0.20,0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00; and A2can be 10.00, 8.00, 5.00, 4.00, 3.00, 2.00, 1.50, 1.40, 1.30, 1.20,1.10, 1.00, 0.90, 0.80, 0.70, 0.60, 0.50, 0.40, 0.30, 0.20, or 0.10, aslong as A1<A2. Where a precious metal such as Pd, Pt, Ru, Rh, Ir, andthe like, is used, it is desirable that they are used as a relativelylow concentration due to high cost.

It is believed that to provide desired level of hydrogenation function,the hydrogenation metal contained in the catalyst of the presentdisclosure is advantageously in an oxidation state of zero. Thus, in thecatalyst particles used in the present disclosure, at least x % of thehydrogenation metal is in zero oxidation state, where x can be: 80, 82,84, 85, 86, 88, 90, 92, 94, 95, 96, 98, 99, or even 99.5.

In certain embodiments of the catalyst of the present disclosure, atleast AA wt % of the hydrogenation metal is supported on the inorganicoxide, where AA can be: 50, 55, 60, 65, 70, 75, 80, 85, 90, or even 95.It was found that the preferential distribution of the hydrogenationmetal on the inorganic oxide compared to the surface of the molecularsieve would result in better performance of the catalyst in thehydroalkylation reaction. In certain embodiments, the inorganic oxide ispresent in the composite in the form of islets, and the islets aresubstantially uniformly distributed within the composite. In certainembodiments, it is desired that the islets of the inorganic oxide in thecatalyst particle have an average size of BB micrometers, where x

BB

y, where x can be: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18,20, 22, 24, 25, 26, 28, 30, and y can be: 40, 38, 36, 35, 34, 32, 30,28, 26, 25, 24, 22, 20, 18, 16, 15, 14, 12, or 10, as long as x<y.

In one embodiment, the catalyst particles are made by a catalystfabrication process comprising: (I) forming a mixture comprising thesolid acid and the inorganic oxide; (II) forming a pellet form themixture; (III) depositing a source material of the hydrogenation metalonto the pellet; and (IV) calcining the pellet after step (III) at atemperature in the range from 400° C. to 1000° C. In specificembodiments, the catalyst fabrication process further comprises, afterstep (IV): (V) activating the calcined pellet in the presence of anatmosphere comprising H₂. In more specific embodiments, in step (III),the source material of the hydrogenation metal comprises PdCl₂, and step(II) comprises impregnating the pellet with an aqueous PdCl₂ dispersionhaving a pH in the range from 0 to 4.

The particles such as pellets can be formed by using methods such asextrusion, molding, casting, and the like. Complex particle geometry andvarious sizes can be achieved using forming methods known in the art.For example, extrusion can be used to form “noodle-like” pellets, whichmay be further optionally diced to obtain the pellets with desiredsizes.

The source material of the hydrogenation metal can be advantageously asalt of the metal, which can be present in a liquid dispersion such asan aqueous solution, an emulsification, or a suspension. Advantageously,the distribution of the salt material in the dispersion is substantiallyuniform, which would desirably result in a substantially uniformdistribution thereof on the surface of the relevant particles at the endof the depositing step. The liquid dispersion may advantageouslycomprise other components than a solvent and the source material such asa pH modifier. For example, a PdCl₂ solution may advantageously compriseHCl such that the pH of the solution is from 0 to 4. This pH range wasfound to be particularly beneficial for a uniform deposition of PdCl₂ onthe surface of the relevant particles. The deposition can be effected byimpregnating the particles with the dispersion, spraying the dispersionto the particles, and the like.

To achieve preferential distribution of the hydrogenation metal in therim portion and/or outer portion compared to the center portion of thecatalyst pellet, it is highly desired that in the deposition step, thesource material is deposited preferentially to the rim portion and/orouter portion of the particle prior to calcination. To that end, one canadjust the method of deposition, such as the amount of the dispersionused, and contact time between the dispersion and the particle, thetemperature of the dispersion and the particle during deposition, therotating speed of the particles during deposition, and the like, so thatthe rim portion and/or outer portion thereof is wetted to a greaterextent than the center portion by the dispersion of the source materialof the hydrogenation metal in the depositing step. At the end of thedepositing step, the as-formed particles prior to calcination maycomprise, in addition to the inorganic oxide and/or the solid acid,and/or the source material of the hydrogenation metal, additionalmaterials such as organic binders, surfactants, and the like. Theas-formed particles may be dried prior to calcination, at a temperaturein the range from Ta ° C. to Tb ° C., where Ta can be 0, 5, 10, 15, 20,25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100; andTb can be 200, 195, 190, 185, 180, 175, 170, 165, 160, 155, 150, 145,140, 135, 130, 125, 120, 115, 110, 105, or 100, as long as Ta<Tb. Suchdrying can be advantageously conduced in air.

The calcining step is advantageously a high-temperature treatmentcarried out in the presence of an O₂-containing gas such as air. In thisstep, organic materials contained in the relevant particles are reducedor eliminated, water and/or other solvents are driven off, the particlesare dried, and the hydrogenation metal is redistributed on the surfaceand at least part of the bulk of the particles. Calcination can becarried out at a temperature in a range from T1° C. to T2° C., where T1can be: 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800; and T2can be: 1000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, and400, as long as T1<T2.

Upon calcination, the hydrogenation metal is normally present on/in theparticles at least partly at an oxidation state higher than zero. Thus,for example, where PdCl₂ is the source material of Pd, upon depositionand calcination, the Pd metal may be present in the form of PdCl₂, PdO,and the like, on or in the particle. Without intending to be bound by aparticular theory, it is believed that the hydrogenation metal isdesired to be at zero oxidation state when in active form for catalyzingthe hydrogenation reaction. Thus, it is desired that in certainembodiments, after the final calcination of the catalyst particles andprior to use, the particles are subjected to a step of activation, wherethey are heated in a reducing atmosphere, such as a H₂-containingatmosphere, e.g., pure H₂, H₂/N₂ mixture, H₂/CH₄ mixture, H₂/CH₄/N₂mixture, and the like. Desirably, the reducing atmosphere is a flowingstream of gas. Desirably, the reducing atmosphere comprises water at aconcentration of at most A wt % (based on the total weight of thereducing atmosphere), where A can be 1.0, 0.1, 0.01, 0.005, 0.001,0.0005, 0.0001, 0.00005, or even 0.00001, so that the catalyst particlesare dried and purged of water produced during the activation step, ifany. After this step, the oxidation state of at least a great majority,such as at least X %, where X can be 70, 75, 80, 85, 90, 95, 98, 99, oreven 99.9, of the hydrogenation metal is zero. The activated catalystmay then be protected by an inert atmosphere or reducing atmosphereessentially free of O₂ before use in the hydroalkylation reaction, sothat further oxidation thereof is prevented.

In the hydroalkylation reaction using the catalyst of the presentdisclosure, in addition to the desired alkylated aromatic product,by-products may be produced. For example, the aromatic feed material maybe overly hydrogenated to yield an aliphatic compound. In the case ofbenzene hydroalkylation, benzene may be hydrogenated to formcyclohexane. The aliphatic compound (e.g., cyclohexane) is desirablydehydrogenated to form the aromatic compound feed, which is recycled tothe hydroalkylation process, so as to increase the overall yield of thealkylated aromatic compound product. The alkylated aromatic compound canthen be used to make various products. For example, cyclohexylbenzene,as a desired product of benzene hydroalkylation, may be oxidized to formhydroperoxide thereof, which is then subject to a cleavage reaction tomake phenol and cyclohexanone.

The alkylation process may result in multiple products at variousamounts, e.g., mono-, di-, and tri-alkylated aromatic compounds, and thelike. Depending on the end application, one of more of these productsmay be the desired target compounds. For example, benzenehydroalkylation may produce mono-cyclohexylbenzene, DiCHB (including thevarious isomers described above), and TriCHB (including the variousisomers described above). Thus, the processes and catalyst of thepresent disclosure may be used for making one or more of these products.Where mono-alkylated product such as mono-cyclohexylbenzene is the onlydesired target product, the DiCHB and TriCHB may be subjected totransalkylation in the presence of a transalkylation catalyst such as asolid acid (e.g., faujasite), where DiCHB reacts with benzene to producemono-cyclohexylbenzene, and TriCHB reacts with benzene to producemono-cyclohexylbenzene and DiCHB.

The present invention is particularly useful in making cyclohexylbenzeneby benzene hydroalkylation. The cyclohexylbenzene can then by oxidizedto a hydroperoxide thereof, which is then subjected to cleavage to makephenol and cyclohexanone. The following is a detailed description ofthis embodiment.

Supply of Cyclohexylbenzene

The cyclohexylbenzene supplied to the oxidation step can be producedand/or recycled as part of an integrated process for producing phenoland cyclohexanone from benzene. In such an integrated process, benzeneis initially converted to cyclohexylbenzene by any conventionaltechnique, including oxidative coupling of benzene to make biphenylfollowed by hydrogenation of the biphenyl. However, in practice, thecyclohexylbenzene is desirably produced by contacting benzene withhydrogen under hydroalkylation conditions in the presence of ahydroalkylation catalyst whereby benzene undergoes the followingReaction-1 to produce cyclohexylbenzene (CHB):

Alternatively, cyclohexylbenzene can be produced by direct alkylation ofbenzene with cyclohexene in the presence of a solid-acid catalyst suchas molecular sieves in the MCM-22 family according to the followingReaction-2:

U.S. Pat. Nos. 6,730,625 and 7,579,511, WO2009/131769, and WO2009/128984disclose processes for producing cyclohexylbenzene by reacting benzenewith hydrogen in the presence of a hydroalkylation catalyst, thecontents of all of which are incorporated herein by reference in theirentirety.

The catalyst employed in the hydroalkylation reaction is a bifunctionalcatalyst comprising a molecular sieve, such as one of the MCM-22 typedescribed above and a hydrogenation metal.

Any known hydrogenation metal may be employed in the hydroalkylationcatalyst, specific, non-limiting, suitable examples of which include Pd,Pt, Rh, Ru, Ir, Ni, Zn, Sn, Co, with Pd being particularly advantageous.Desirably, the amount of hydrogenation metal present in the catalyst isfrom 0.05 wt % to 10.0 wt %, such as from 0.10 wt % and 5.0 wt %, of thetotal weight of the catalyst.

In addition to the molecular sieve and the hydrogenation metal, thehydroalkylation catalyst may comprise one or more optional inorganicoxide support materials and/or binders. Suitable inorganic oxide supportmaterial(s) include, but are not limited to, clay, non-metal oxides,and/or metal oxides. Specific, non-limiting examples of such supportmaterials include: SiO₂, Al₂O₃, ZrO₂, Y₂O₃, Gd₂O₃, SnO, SnO₂, andmixtures, combinations and complexes thereof.

The effluent from the hydroalkylation reaction (hydroalkylation reactionproduct mixture) or from the alkylation reaction (alkylation reactionproduct mixture) may contain some polyalkylated benzenes, such asdicyclohexylbenzenes (DiCHB), tricyclohexylbenzenes (TriCHB),methylcyclopentylbenzene, unreacted benzene, cyclohexane, bicyclohexane,biphenyl, and other contaminants. Thus, typically, after the reaction,the hydroalkylation reaction product mixture is separated bydistillation to obtain a C6 fraction containing benzene, cyclohexane, aC12 fraction containing cyclohexylbenzene and methylcyclopentylbenzene,and a heavies fraction containing, e.g., C18s such as DiCHBs and C24ssuch as TriCHBs. The unreacted benzene may be recovered by distillationand recycled to the hydroalkylation or alkylation reactor. Thecyclohexane may be sent to a dehydrogenation reactor, with or withoutsome of the residual benzene, and with or without co-fed hydrogen, whereit is converted to benzene and hydrogen, which can be recycled to thehydroalkylation/alkylation step.

Depending on the quantity of the heavies fraction, it may be desirableto either (a) transalkylate the C18s such as DiCHB and C24s such asTriCHB with additional benzene or (b) dealkylate the C18s and C24s tomaximize the production of the desired monoalkylated species.

Transalkylation with additional benzene is desirably effected in atransalkylation reactor, which is separate from the hydroalkylationreactor, over a suitable transalkylation catalyst, such as a molecularsieve of the MCM-22 type, zeolite beta, MCM-68 (see U.S. Pat. No.6,049,018), zeolite Y, zeolite USY, and mordenite. The transalkylationreaction is desirably conducted under at least partially liquid phaseconditions, which suitably include a temperature in the range from 100°C. to 300° C., a pressure in the range from 800 kPa to 3500 kPa, aweight hourly space velocity from 1 hr⁻¹ to 10 hr⁻¹ on total feed, and abenzene/dicyclohexylbenzene weight ratio in a range from 1:1 to 5:1.

Dealkylation is also desirably effected in a reactor separate from thehydroalkylation reactor, such as a reactive distillation unit, at atemperature of about 150° C. to about 500° C. and a pressure in a rangefrom 15 to 500 psig (200 to 3550 kPa) over an acid catalyst such as analuminosilicate, an aluminophosphate, a silicoaluminophosphate,amorphous silica-alumina, an acidic clay, a mixed metal oxide, such asWO_(x)/ZrO₂, phosphoric acid, sulfated zirconia and mixtures thereof.Desirably, the acid catalyst includes at least one aluminosilicate,aluminophosphate or silicoaluminophosphate of the FAU, AEL, AFI and MWWfamily. Unlike transalkylation, dealkylation can be conducted in theabsence of added benzene, although it may be desirable to add benzene tothe dealkylation reaction to reduce coke formation. In this case, theweight ratio of benzene to poly-alkylated aromatic compounds in the feedto the dealkylation reaction can be from 0 to about 0.9, such as fromabout 0.01 to about 0.5. Similarly, although the dealkylation reactioncan be conducted in the absence of added hydrogen, hydrogen is desirablyintroduced into the dealkylation reactor to assist in coke reduction.Suitable hydrogen addition rates are such that the molar ratio ofhydrogen to poly-alkylated aromatic compound in the total feed to thedealkylation reactor can be from about 0.01 to about 10.

The transalkylation or dealkylation product mixture comprising benzene,C12s and heavies can then be separated to obtain a C6 fraction, whichcomprises primarily benzene and can be recycled to thehydroalkylation/alkylation step, a C12s fraction comprising primarilycyclohexylbenzene, and a heavies fraction which can be subjected to atransalkylation/dealkylation reaction again or discarded.

The cyclohexylbenzene freshly produced and/or recycled may be purifiedbefore being fed to the oxidation step to remove at least a portion of,among others, methylcyclopentylbenzene, olefins, phenol, acid, and thelike. Such purification may include, e.g., distillation, hydrogenation,caustic wash, and the like.

The cyclohexylbenzene feed to the oxidizing step may contain, based onthe total weight of the feed, one or more of the following: (i)bicyclohexane at a concentration in a range from at 1 ppm to 1 wt %,such as from 10 ppm to 8000 ppm; (ii) biphenyl at a concentration in arange from 1 ppm to 1 wt %, such as from 10 ppm to 8000 ppm; (iii) waterat a concentration up to 5000 ppm, such as from 100 ppm to 1000 ppm; and(iv) olefins or alkene benzenes, such as phenylcyclohexene, at aconcentration no greater than 1000 ppm.

Oxidation of Cyclohexylbenzene

In the oxidation step, at least a portion of the cyclohexylbenzenecontained in the oxidation feed is converted tocyclohexyl-1-phenyl-1-hydroperoxide, the desired hydroperoxide,according to the following Reaction-3:

In exemplary processes, the oxidizing step may be accomplished bycontacting an oxygen-containing gas, such as air and various derivativesof air, with the feed comprising cyclohexylbenzene. For example, astream of pure O₂, O₂ diluted by inert gas such as N₂, pure air, orother O₂-containing mixtures can be pumped through thecyclohexylbenzene-containing feed in an oxidation reactor.

The oxidation may be conducted in the absence or presence of a catalyst.Examples of suitable oxidation catalysts include those having astructure of formula (FC-I), (FC-II), or (FC-III) below:

where:

A represents a ring optionally comprising a nitrogen, sulfur, or oxygenin the ring structure, and optionally substituted by an alkyl, analkenyl, a halogen, or a N-, S-, or O-containing group or other group;

X represents a hydrogen, an oxygen free radical, a hydroxyl group, or ahalogen;

R¹, the same or different at each occurrence, independently represents ahalogen, a N-, S-, or O-containing group, or a linear or branchedacyclic alkyl or cyclic alkyl group having 1 to 20 carbon atoms,optionally substituted by an alkyl, an alkenyl, a halogen, or a N-, S-,or O-containing group or other group; and

m is 0, 1 or 2.

Examples of particularly suitable catalysts for the oxidation stepinclude those represented by the following formula (FC-IV):

where:

R², the same or different at each occurrence, independently represents ahalogen, a N-, S-, or O-containing group, or an optionally substitutedlinear or branched acyclic alkyl or cyclic alkyl group having 1 to 20carbon atoms; and

n is 0, 1, 2, 3, or 4.

One especially suitable catalyst having the above formula (FC-IV) forthe oxidation step is NHPI (N-hydroxyphthalimide). For example, the feedto the oxidizing step can comprise from 10 to 2500 ppm of NHPI by weightof the cyclohexylbenzene in the feed.

Other non-limiting examples of the oxidation catalyst include:4-amino-N-hydroxyphthalimide, 3-amino-N-hydroxyphthalimide,tetrabromo-N-hydroxyphthalimide, tetrachloro-N-hydroxyphthalimide,N-hydroxyhetimide, N-hydroxyhimimide, N-hydroxytrimellitimide,N-hydroxybenzene-1,2,4-tricarboximide, N,N′-dihydroxy(pyromelliticdiimide), N,N′-dihydroxy(benzophenone-3,3′,4,4′-tetracarboxylicdiimide), N-hydroxymaleimide, pyridine-2,3-dicarboximide,N-hydroxysuccinimide, N-hydroxy(tartaric imide),N-hydroxy-5-norbornene-2,3-dicarboximide,exo-N-hydroxy-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboximide,N-hydroxy-cis-cyclohexane-1,2-dicarboximide,N-hydroxy-cis-4-cyclohexene-1,2 dicarboximide, N-hydroxynaphthalimidesodium salt, N-hydroxy-o-benzenedisulphonimide, andN,N′,N″-trihydroxyisocyanuric acid.

These oxidation catalysts can be used either alone or in conjunctionwith a free radical initiator, and further can be used as liquid-phase,homogeneous catalysts or can be supported on a solid carrier to providea heterogeneous catalyst. Desirably, the N-hydroxy substituted cyclicimide or the N,N′,N″-trihydroxyisocyanuric acid is employed in an amountfrom 0.0001 wt % to 15 wt %, such as from 0.001 wt % to 5 wt %, of thecyclohexylbenzene feed.

Non-limiting examples of suitable reaction conditions of the oxidizingstep include a temperature in a range from 70° C. to 200° C., such as90° C. to 130° C., and a pressure in a range from 50 kPa to 10,000 kPa.A basic buffering agent may be added to react with acidic by-productsthat may form during the oxidation. In addition, an aqueous phase may beintroduced into the oxidation reactor. The reaction may take place in abatch or continuous flow fashion.

The reactor used for the oxidizing step may be any type of reactor thatallows for the oxidation of cyclohexylbenzene by an oxidizing agent,such as molecular oxygen. A particularly advantageous example of thesuitable oxidation reactor is a bubble column reactor capable ofcontaining a volume of the reaction media and bubbling an O₂-containinggas stream (such as air) through the media. For example, the oxidationreactor may comprise a simple, largely open vessel with a distributorinlet for the oxygen-containing gas stream. The oxidation reactor mayhave means to withdraw a portion of the reaction media and pump itthrough a suitable cooling device and return the cooled portion to thereactor, thereby managing the heat generated in the reaction.Alternatively, cooling coils providing indirect cooling, e.g., bycooling water, may be operated within the oxidation reactor to remove atleast a portion of the generated heat. Alternatively, the oxidationreactor may comprise a plurality of reactors in series and/or inparallel, each operating at the same or different conditions selected toenhance the oxidation reaction in the reaction media with differentcompositions. The oxidation reactor may be operated in a batch,semi-batch, or continuous flow manner well known to those skilled in theart.

Composition of the Oxidation Reaction Product Mixture

Desirably, the oxidation reaction product mixture exiting the oxidationreactor contains cyclohexyl-1-phenyl-1-hydroperoxide at a concentrationin a range from Chp1 wt % to Chp2 wt %, based on the total weight of theoxidation reaction product mixture, where Chp1 and Chp2 can be,independently, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70,75, 80, as long as Chp1<Chp2. Preferably, the concentration ofcyclohexyl-1-phenyl-1-hydroperoxide in the oxidation reaction productmixture is at least 20% by weight of the oxidation reaction productmixture. The oxidation reaction product mixture may further compriseresidual cyclohexylbenzene at a concentration in a range from Cchb1 wt %to Cchb2 wt %, based on the total weight of the oxidation reactionproduct mixture, where Cchb1 and Cchb2 can be, independently, 20, 25,30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, as long asCchb1<Cchb2. Preferably, the concentration of cyclohexylbenzene in theoxidation reaction product mixture is at most 65% by weight of theoxidation reaction product mixture.

In addition, the oxidation reaction product mixture may contain one ormore hydroperoxides other than cyclohexyl-1-phenyl-1-hydroperoxidegenerated as byproduct(s) of the oxidation reaction ofcyclohexylbenzene, or as the oxidation reaction product of oxidizablecomponent(s) other than cyclohexylbenzene that may have been containedin the feed supplied to the oxidizing step, such ascyclohexyl-2-phenyl-1-hydroperoxide,cyclohexyl-3-phenyl-1-hydroperoxide, and methylcyclopentylbenzenehydroperoxides. These undesired hydroperoxides are present at a totalconcentration from Cu1 wt % to Cu2 wt %, where Cu1 and Cu2 can be,independently, 0.1, 0.2, 0.3, 0.5, 0.7, 0.9, 1.0, 1.2, 1.4, 1.5, 1.6,1.8, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 7.0, 8.0, as long asCu1<Cu2. They are undesirable because they may not convert into phenoland cyclohexanone in the cleavage reaction at the desired conversionand/or selectivity, resulting in overall yield loss.

As noted above, the oxidation reaction product mixture may also containphenol as a further by-product of the oxidation reaction. Theconcentration of phenol (CPh) in the oxidation reaction product mixtureexiting the oxidation reactor(s) can range from CPh1 ppm to CPh2 ppm,where CPh1 and CPh2 can be, independently: 50, 60, 70, 80, 90, 100, 150,200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850,900, 950, 1000, 1500, 2000, as long as CPh1<CPh2.

The oxidation reaction product mixture may contain water. Theconcentration of water in the oxidation reaction product mixture exitingthe oxidation reactor may range from C1a ppm to C1b ppm, based on thetotal weight of the oxidation reaction product mixture, where C1a andC1b can be, independently: 30, 40, 50, 60, 70, 80, 90, 100, 150, 200,250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900,950, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, or 5000, as long asC1a<C1b.

The oxidation reaction product mixture may also contain part or all ofany catalyst, such as NHPI, supplied to the oxidizing step. For example,the oxidation reaction product mixture may contain from 10 to 2500 ppmof NHPI, such as from 100 to 1500 ppm by weight of NHPI.

Treatment of the Oxidation Reaction Product Mixture

In the process of the present disclosure, before being supplied to thecleavage step, at least a portion of the oxidation reaction productmixture may be separated. The separation process may include subjectingat least a portion of the oxidation reaction product mixture to vacuumevaporation so as to recover: (i) a first fraction comprising themajority of the cyclohexyl-1-phenyl-1-hydroperoxide and other higherboiling components of the oxidation reaction product mixture portion,such as other hydroperoxides and NHPI catalyst, if present in theoxidation reaction product mixture portion; and (ii) a second fractioncomprising a major portion of the cyclohexylbenzene, phenol, if any, andother lower boiling components of the oxidation reaction product mixtureportion.

Desirably, in the first fraction, the concentration ofcyclohexyl-1-phenyl-1-hydroperoxide can range from Cc1 wt % to Cc2 wt %,and the concentration of cyclohexylbenzene can range from Cd1 wt % toCd2 wt %, based on the total weight of the first fraction, where Cc1 andCc2 can be, independently, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90,as long as Cc1<Cc2; and Cd1 and Cd2 can be, independently, 10, 15, 20,25, 30, 35, 40, 45, 50, as long as Cd1<Cd2.

Advantageously, in the second fraction, the concentration ofcyclohexyl-1-phenyl-1-hydroperoxide can range from Cc3 wt % to Cc4 wt %,and the concentration of cyclohexylbenzene can range from Cd3 wt % toCd4 wt %, based on the total weight of the second fraction, where Cc3and Cc4 can be, independently, 0.01, 0.05, 0.10, 0.20, 0.40, 0.50, 0.60,0.80, 1.00, 1.50, 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, as long asCc3<Cc4; and Cd3 and Cd4 can be, independently, 90, 92, 94, 95, 96, 97,98, or even 99, as long as Cd3<Cd4.

Because cyclohexylbenzene hydroperoxide is prone to decomposition atelevated temperatures, e.g., at above 150° C., the vacuum evaporationstep to separate the oxidation reaction product mixture into the firstand second fractions is conducted at a relatively low temperature, e.g.,no higher than 130° C., or no higher than 120° C., or even no higherthan 110° C. Cyclohexylbenzene has a high boiling point (239° C. at 101kPa). Thus, at acceptable cyclohexylbenzene-removal temperatures,cyclohexylbenzene tends to have very low vapor pressure. Accordingly,preferably, to effectively remove a meaningful amount ofcyclohexylbenzene from the oxidation reaction product mixture, theoxidation reaction product mixture is subjected to a very low absolutepressure, e.g., in a range from Pc1 kPa to Pc2 kPa, where Pc1 and Pc2can be, independently, 0.05, 0.10, 0.15, 0.20, 0.25, 0.26, 0.30, 0.35,0.40, 0.45, 0.50, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00,1.50, 2.00, 2.50, 3.00, as long as Pc1<Pc2. Particularly advantageously,Pc1=0.25, and Pc2=1.5.

After separation of the oxidation reaction product mixture into thefirst and second fractions, part or all of the first fraction can berouted directly to the cleavage step. All or a portion of the firstfraction may be cooled before passage to the cleavage step so as tocause crystallization of the unreacted imide oxidation catalyst. Theimide crystals may then be recovered for reuse either by filtration orby scraping from a heat exchanger surface used to effect thecrystallization.

The second fraction produced from the oxidation reaction product mixturemay be treated to reduce the level of phenol therein before part or allof the cyclohexylbenzene in the second fraction is recycled to thehydrogenation.

Treatment of the second fraction can comprise contacting at least aportion of the second fraction with an aqueous composition comprising abase under conditions such that the base reacts with the phenol toproduce a phenoate species which remains in the aqueous composition. Astrong base, that is a base having a pK_(b) value less than 3, such asless than 2, 1, 0, or −1, is desirably employed in the treatment of thesecond fraction. Particularly suitable bases include hydroxides ofalkali metals (e.g., LiOH, NaOH, KOH, RbOH), hydroxides of alkalineearth metals (Mg(OH)₂, Ca(OH)₂, Sr(OH)₂, Ba(OH)₂), and mixtures of oneor more thereof. Phenol can react with these hydroxides to formphenoates, which typically have higher solubility in water than phenolper se. A particularly desirable base is NaOH, which is cost efficientand capable of reacting with phenol in the second fraction to producesodium phenoate. It should be noted that, when a hydroxide is used asthe base, because of the reaction of CO₂ present in the atmosphere withthe hydroxide, the aqueous composition may comprise, at variousconcentrations, one or more of a corresponding carbonate, bicarbonate,or carbonate-hydroxide complex. Desirably, the aqueous compositioncomprising the base has a pH of at least 8, preferably at least 10.

Contacting of the second fraction with the aqueous compositioncomprising a base produces an aqueous phase containing at least part ofthe phenol and/or a derivative thereof from the second fraction and anorganic phase containing cyclohexylbenzene and having a reducedconcentration of phenol as compared with the second fraction. Desirably,the phenol concentration in the organic phase is in the range from CPh7ppm to CPh8 ppm, based on the total weight of the organic phase, whereCPh7 and CPh8 can be, independently: 0, 10, 20, 30, 40, 50, 100, 150,200, 250, as long as CPh7<CPh8.

The organic phase can then be separated from the aqueous phase, forexample, spontaneously under gravity, and can then be recycled to theoxidizing step as a third fraction either directly, or more preferably,after water washing to remove base entrained in the organic phase.

Cleavage Reaction

In the cleavage reaction, at least a portion of thecyclohexyl-1-phenyl-1-hydroperoxide decomposes in the presence of anacid catalyst in high selectivity to cyclohexanone and phenol accordingto the following desired Reaction-4:

The cleavage product mixture may comprise the acid catalyst, phenol,cyclohexanone, cyclohexylbenzene, and contaminants.

The acid catalyst can be at least partially soluble in the cleavagereaction mixture, is stable at a temperature of at least 185° C. and hasa lower volatility (higher normal boiling point) than cyclohexylbenzene.

Acid catalysts preferably include, but are not limited to, Bronstedacids, Lewis acids, sulfonic acids, perchloric acid, phosphoric acid,hydrochloric acid, p-toluene sulfonic acid, aluminum chloride, oleum,sulfur trioxide, ferric chloride, boron trifluoride, sulfur dioxide, andsulfur trioxide. Sulfuric acid is a preferred acid catalyst.

The cleavage reaction preferably occurs under cleavage conditionsincluding a temperature in a range from 20° C. to 200° C., or from 40°C. to 120° C., and a pressure in a range from 1 to 370 psig (at least 7kPa, gauge and no greater than 2,550 kPa, gauge), or from 14.5 psig to145 psig (from 100 kPa, gauge to 1,000 kPa, gauge) such that thecleavage reaction mixture is completely or predominantly in the liquidphase during the cleavage reaction.

The cleavage reaction mixture can contain the acid catalyst at aconcentration in a range from Cac1 ppm to Cac2 ppm by weight of thetotal weight of the cleavage reaction mixture, where Cac1 and Cac2 canbe, independently, 10, 20, 30, 40, 50, 60, 80, 100, 150, 200, 250, 300,350, 400, 450, 500, 600, 700, 800, 900, 1000, 1500, 2000, 2500, 3000,3500, 4000, 4500, or even 5000, as long as Cac1<Cac2. Preferably, Cac1is 50, and Cac2 is 200.

Conversion of hydroperoxides, such ascyclohexyl-1-phenyl-1-hydroperoxide, and conveniently allcyclohexyl-1-phenyl-1-hydroperoxide and other hydroperoxides, may bevery high in the cleavage reaction, e.g., at least AA wt %, where AA canbe 90.0, 91.0, 92.0, 93.0, 94.0, 95.0, 96.0, 97.0, 98.0, 99.0, 99.5,99.9, or even 100, the percentage based on the weight of a givenhydroperoxide, or of all hydroperoxides fed to the cleavage step. Thisis desirable because any hydroperoxide, even thecyclohexyl-1-phenyl-1-hydroperoxide, becomes a contaminant in thedownstream processes.

Desirably, each mole of cyclohexyl-1-phenyl-1-hydroperoxide produces onemole of phenol and one mole of cyclohexanone. However, due to sidereactions, the selectivity of the cleavage reaction to phenol can rangefrom Sph1% to Sph2% and the selectivity to cyclohexanone can range fromSch1% to Sch2%, where Sph1, Sph2, Sch1, and Sch2 can be, independently,85, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or even 99.5, aslong as Sph1<Sph2, and Sch1<Sch2.

Besides the cleavage feed comprising cyclohexylbenzene hydroperoxide,cyclohexylbenzene and other components originating directly from theoxidation reaction product mixture, the cleavage reaction mixture mayfurther comprise other added materials, such as the cleavage catalyst, asolvent, and one or more products of the cleavage reaction such asphenol and cyclohexanone recycled from the cleavage product mixture, orfrom a downstream separation step. Thus, the cleavage reaction mixtureinside the cleavage reactor may comprise, based on the total weight ofthe cleavage reaction mixture: (i) phenol at a concentration from CPh9wt % to CPh10 wt %, where CPh9 and CPh10 can be, independently, 20, 25,30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80, as long as CPh9<CPh10;(ii) cyclohexanone at a concentration from Cch1 wt % to Cch2 wt %, whereCch1 and Cch2 can be, independently, 20, 25, 30, 35, 40, 45, 50, 55, 60,65, 70, 75, or 80, as long as Cch1<Cch2; and (iii) cyclohexylbenzene ata concentration from Cchb7 wt % to Cchb8 wt %, where Cchb7 and Cchb8 canbe, independently, 5, 8, 9, 10, 12, 14, 15, 18, 20, 22, 24, 25, 26, 28,30, 35, 40, 45, 50, 55, 60, 65, 70, as long as Cchb7<Cchb8.

The reactor used to effect the cleavage reaction (i.e., the cleavagereactor) may be any type of reactor known to those skilled in the art.For example, the cleavage reactor may be a simple, largely open vesseloperating in a near-continuous stirred tank reactor mode, or a simple,open length of pipe operating in a near-plug flow reactor mode. Thecleavage reactor may comprise a plurality of reactors in series, eachperforming a portion of the conversion reaction, optionally operating indifferent modes and at different conditions selected to enhance thecleavage reaction at the pertinent conversion range. The cleavagereactor can be a catalytic distillation unit.

The cleavage reactor can be operable to transport a portion of thecontents through a cooling device and return the cooled portion to thecleavage reactor, thereby managing the exothermicity of the cleavagereaction. Alternatively, the reactor may be operated adiabatically.Cooling coils operating within the cleavage reactor(s) can be used to atleast a part of the heat generated.

The cleavage product mixture exiting the cleavage reactor may comprise,based on the total weight of the cleavage product mixture: (i) phenol ata concentration from CPh11 wt % to CPh12 wt %, where CPh11 and CPh12 canbe, independently, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or80, as long as Ch11<CPh12; (ii) cyclohexanone at a concentration fromCch3 wt % to Cch4 wt %, where Cch3 and Cch4 can be, independently, 20,25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80, as long as Cch3<Cch4;and (iii) cyclohexylbenzene at a concentration from Cchb9 wt % to Cchb10wt %, where Cchb9 and Cchb10 can be, independently, 5, 8, 9, 10, 12, 14,15, 18, 20, 22, 24, 25, 26, 28, 30, 35, 40, 45, 50, 55, 60, 65, 70, aslong as Cchb9<Cchb10.

Separation and Purification

As discussed above, the cleavage product mixture may comprise one ormore contaminants. In embodiments disclosed herein, the processesfurther comprise contacting at least a portion of a contaminant with anacidic material to convert at least a portion of the contaminant to aconverted contaminant, thereby producing a modified product mixture.Detailed description of the contaminant treatment process can be found,e.g., in International Publication WO2012/036822A1, the relevant contentof which is incorporated herein by reference in its entirety.

At least a portion of the cleavage product mixture may be subjected to aneutralization reaction. Where a liquid acid such as sulfuric acid isused as the cleavage catalyst, it is highly desirable that the cleavagereaction product mixture is neutralized by a base, such as an organicamine (e.g., methylamine, ethylamine, diamines such as methylenediamine,propylene diamine, butylene diamine, pentylene diamine, hexylenediamine, and the like) before the mixture is subjected to separation toprevent equipment corrosion by the acid. Desirably, the thus formedamine sulfate salt has a boiling point higher than that ofcyclohexylbenzene.

The neutralized cleavage reaction product mixture can then be separatedby methods such as distillation. In one example, in a first distillationcolumn after the cleavage reactor, a heavies fraction comprising theamine salt is obtained at the bottom of the column, a side fractioncomprising cyclohexylbenzene is obtained in the middle section, and anupper fraction comprising cyclohexanone, phenol, methylcyclopentanone,and water is obtained.

The separated cyclohexylbenzene fraction can then be treated and/orpurified before being delivered to the oxidizing step. Since thecyclohexylbenzene separated from the cleavage product mixture maycontain phenol and/or olefins such as cyclohexenylbenzenes, the materialmay be subjected to treatment with an aqueous composition comprising abase as described above for the second fraction of the oxidation productmixture and/or a hydrogenation step as disclosed in, for example,WO2011/100013A1, the entire contents of which are incorporated herein byreference.

In one example, the fraction comprising phenol, cyclohexanone, and watercan be further separated by simple distillation to obtain an upperfraction comprising primarily cyclohexanone and methylcyclopentanone anda lower stream comprising primarily phenol, and some cyclohexanone.Cyclohexanone cannot be completely separated form phenol without usingan extractive solvent due to an azeotrope formed between these two.Thus, the upper fraction can be further distillated in a separate columnto obtain a pure cyclohexanone product in the vicinity of the bottom andan impurity fraction in the vicinity of the top comprising primarilymethylcyclopentanone, which can be further purified, if needed, and thenused as a useful industrial material. The lower fraction can be furtherseparated by a step of extractive distillation using an extractivesolvent (e.g., glycols such as ethylene glycol, propylene glycol,diethylene glycol, triethylene glycol, and the like) described in, e.g.,co-assigned, co-pending patent applications WO2013/165656A1 andWO2013/165659, the contents of which are incorporated herein byreference in their entirety. An upper fraction comprising cyclohexanoneand a lower fraction comprising phenol and the extractive solvent can beobtained. In a subsequent distillation column, the lower fraction canthen be separated to obtain an upper fraction comprising a phenolproduct and a lower fraction comprising the extractive solvent.

Uses of Cyclohexanone and Phenol

The cyclohexanone produced through the processes disclosed herein may beused, for example, as an industrial solvent, as an activator inoxidation reactions and in the production of adipic acid, cyclohexanoneresins, cyclohexanone oxime, caprolactam, and nylons, such as nylon-6and nylon-6,6.

The phenol produced through the processes disclosed herein may be used,for example, to produce phenolic resins, bisphenol A, ε-caprolactam,adipic acid, and/or plasticizers.

The following non-limiting examples further illustrate the presentinvention. While the use of the catalyst prepared in the examples wereonly tested in benzene hydroalkylation processes, it is expected thatthe same catalyst would function similarly for the hydroalkylation ofother aromatic compounds, such as alkylated benzenes (e.g., toluene,ethylbenzene, xylene, propylbenzene, and the like), naphthalene, andalkylated naphthalenes (e.g., methyl naphthalene, and the like).

Examples

In the Examples, Pd/MCM-49/Al₂O₃ catalysts having a preferential Pddistribution in the rim portion and/or outer portion of the catalystparticles (also called pellets herein) were prepared, characterized ofthe Pd distribution, and evaluated for performance in benzenehydroalkylation to produce cyclohexylbenzene.

1. Catalyst Preparation

Preparation of Catalyst A

A first rimmed catalyst (Catalyst A) comprising 0.15 wt % Pd on 80%MCM-49 and 20 wt % Al₂O₃ was prepared according to the followingprocedure.

-   -   a. 2.30 g of a palladium chloride solution (also containing HCl)        at a Pd concentration of 19.538 wt %, commercially available        from Johnson Matthey, was diluted with 327.79 g of deionized        water. The pH of the combined palladium chloride and deionized        water was measured to be 3.04.    -   b. 300 grams of a 1/20 inch (1.27 mm) quadrulobe extrudate        comprising 80 wt % MCM-49, 20 wt % alumina was added to a        laboratory tablet coater available from A. E. Aubin as Model        #1600.    -   c. The tablet coater was rotated at an rpm of 30.    -   d. The palladium chloride solution prepared in step (a) was        sprayed onto the rotating extrudate at 60 mL per minute.    -   e. The wet extrudate continued to mix for an additional 30        minutes at a rotational speed of 10 rpm.    -   f. After mixing, the wet extrudate was dried for 20 hours at        120° C. in an oven available from Desptach.    -   g. The metal dispersion of the dried extrudate (0.15 wt % Pd)        was measured by using a Micromeritics ASAP2100 chemisorption        instrument using oxygen at a H₂ reduction temperature of 250° C.        The measurement result was 75%.    -   h. The dried extrudate was calcined in flowing air at 538° C.        for three hours. The temperature was ramped from ambient to        538° C. at 1° C. per minute.    -   i. The metal dispersion of the air calcined extrudate        (containing 0.15 wt % Pd) was measured by using a Micromeritics        ASAP2100 chemisorption instrument using oxygen at a H₂ reduction        temperature of 250° C. The measurement result was 72%. The BET        surface area was measured to be 494 m²/g. The loss-on-ignition        at 525° C. was measured to be 0.7 wt %.

1.2 Preparation of Catalyst B

A second rimmed catalyst, Catalyst B, comprising 0.15 wt % Pd on 80 wt %MCM-49 and 20 wt % Al₂O₃, was prepared according to the followingprocedure.

-   -   a. 2.31 g of a palladium chloride solution (also containing HCl)        at a Pd concentration of 19.480 wt %, commercially available        from Johnson Matthey, was diluted with 327.97 g of deionized        water. The pH of the combined palladium chloride and deionized        water was measured to be 1.96.    -   b. grams of a 1/20 inch (1.27 mm) quadrulobe extrudate        comprising 80 wt % MCM-49, 20 wt % alumina was added to a        laboratory tablet coater available from A. E. Aubin as Model        #1600.    -   c. The tablet coater was rotated at an rpm of 30.    -   d. The palladium chloride solution prepared in step (a) was        sprayed onto the rotating extrudate at 60 mL per minute.    -   e. The wet extrudate continued to mix for an additional 60        minutes at a rotational speed of 10 rpm.    -   f. After mixing, the wet extrudate was dried for 20 hours at        120° C. in an oven available from Desptach.    -   g. The metal dispersion of the dried extrudate (containing 0.15        wt % Pd) was measured by a Micromeritics ASAP2100 chemisorption        instrument using oxygen after a H₂ reduction temperature of        250° C. The measurement result was 77%.    -   h. The dried extrudate was calcined in flowing air at 538° C.        for three hours. The temperature was ramped from ambient to        538° C. at 1° C. per minute.    -   i. The catalyst preparation was repeated ten times in steps (a)        through (h) to obtain ten batches of catalyst materials, which        were then blended together.    -   j. The metal dispersion of the air calcined blended 10 batches        of extrudate (containing 0.15 wt % Pd) was measured by a        Micromeritics ASAP2100 chemisorption instrument using oxygen at        a H₂ reduction temperature of 250° C. The result was 73%. The        BET surface area was measured to be 507 m²/g. The        loss-on-ignition at 525° C. was measured to be 1.1 wt %.

2. Analysis of the Metal Distribution of the Rimmed Catalysts

A Field-Emission Electron Probe Micro Analyzer (EPMA) was utilized togenerate line scans for the catalyst extrudate (also referred to aspellet) cross-sections. Catalyst extrudates were first embedded in a lowviscosity epoxy resin (LR-White) under vacuum to fully impregnate them.The resin was then cured under a flow of N₂ at 60° C. Each cured mountwas cut as shown in FIG. 2. The as-cut surface was then ground usingsilicon carbide grit paper (120 grit-600 grit) and then with siliconcarbide powder (1000 grit) on a napped cloth to achieve a mirror finish.Samples were then coated with ˜200 A of carbon for conductivity.

EPMA conditions: 15 kV accelerating voltage, 150 nA beam currentmeasured with an internal Faraday cup. X-ray diffracting crystals wereused to detect the characteristic X-rays. A typical configuration was asfollows:

Background Position Xtal Element X-Ray Line Standard (mm from peak)LDE2: Carbon Kα₁ (Graphite) +30.363, −35.653 PETL: Chlorine Kα₁ (NaCl)+5.000, −5.000 TAPH: Aluminum Kα₁ (Al₂O₃) +5.000, −5.000 PETL: PalladiumLα₁ (Palladium Metal) +5.000, −5.000 TAP: Silicon Kα₁ (SiO₂) +5.000,−5.000 Oxygen by difference

Peak positions for X-ray lines were determined by scanning the crystalon a standard for each set of analyses. Two background positions werechecked on the sample for interferences by scanning a spectral regionthat encompassed both the peak and background regions. Adjustments tothe peak and background positions were made as necessary to optimize theanalysis (avoid overlaps, etc.).

Counting times on the catalyst pellets were typically 10 seconds onpeak, and 5 seconds on each background. Net counts were calculated foreach position of the beam along the line scan. Concentrations werecalculated using a standard ZAF approach. A quantitative line scan isthus generated across the cross-sectioned pellet. Typically, 10-13micron steps were used and the electron beam was defocused to match thestep size. This resulted in 150 points across the pellet for a typical1.5 mm scan (with 10 micron steps).

Before performing light optical microscopy and/or EPMA analyses, thefresh calcined hydroalkylation catalyst samples were reduced in a fixedbed reactor at 300° C. in flowing 50 psig (344 kPa gauge) H₂ followingthe same procedure as performed before hydroalkylation tests describedbelow. After reduction, the catalyst extrudates were discharged in aN₂-filled glove box, then separated from the quartz diluent and loadedinto sealable glass vials. The closed vials were removed from the glovebox and the screw caps were slightly cracked to allow small quantitiesof air to slowly diffuse into the vial. This procedure provided for acontrolled back-oxidation of the surface of the Pd particles in thecatalyst without oxidizing the bulk of the metal. This so-calledpassivation procedure was performed to avoid uncontrolled oxidation andpotential local overheating that might have affected metal morphologyduring sample handling. The thus-prepared extrudates then wereepoxy-mounted, cross-sectioned and analyzed by EPMA and also imagedunder a light optical microscope to characterize metal distribution.

The cross-sections of the catalyst pellets were found to have roughlysymmetric geometry relative to a center line passing through the centerand the two opposite corners. The line-scan of the EPMA analysis wasperformed along the center line.

FIGS. 4 and 5 depict the EPMA line-scan results for three extrudatesfrom Catalyst A and Catalyst B, respectively. In both figures, thehorizontal axis is the location on normalized extrudate diameter (%),and the vertical axis is local Pd concentration (wt %). For eachcatalyst, three different pellets (401, 403, and 403 in FIG. 4 forCatalyst A, and 501, 503, and 503 in FIG. 5 for Catalyst B) werescanned. It is quite clear that in both figures, the Pd concentrationsare much higher in the rim portions (left rim and right rim) than in thecenter portion. Indeed, both catalysts showed near-zero Pd concentrationin the center portions thereof.

Tables 2.1 and 2.2 below summarize the average metal concentrations inthe left rim portion (Crim(1)), right rim portion (Crim(r)), both rimportions (Crim(av)), and in the center portion (Ccenter) and theirratios for three extrudates from Catalyst A and Catalyst B,respectively. As the results show, the metal distribution within theseextrudates is higher in the rim portions as evidenced by the high (˜500for Catalyst A, and ˜100 or Catalyst B) Crim/Ccenter concentrationratios.

TABLE 2.1 Average metal concentration ratios for the three extrudatesfrom Catalyst A For 20% left and right rim portions and 20% centerPellet Crim(l)/ No. Ccenter Crim(r)/Ccenter Crim(av)/CcenterCrim(l)/Crim(r) 1 399 479 439 0.83 2 105 109 107 0.96 3 1025 851 9381.20 Average 510 480 495 1.00

TABLE 2.2 Average metal concentration ratios for the three extrudatesfrom Catalyst B For 20% left and right rim portions and 20% centerPellet Crim(l)/ No. Ccenter Crim(r)/Ccenter Crim(av)/CcenterCrim(l)/Crim(r) 1 162 167 164 0.97 2 48 58 53 0.83 3 112 133 122 0.84Average 107 119 113 0.88

Tables 2.3 and 2.4 below summarize the average metal concentrations inthe left outer portion (Couter(1)), right outer portion (Couter(r)),both outer portions (Couter(av)), and in the center portion (Ccenter)and their ratios for three extrudates from Catalyst A and Catalyst B,respectively. As the results show, the metal distribution within theseextrudates is higher in the outer portions as evidenced by the high(377-401 for Catalyst A and 74-80 for Catalyst B) Couter/Ccenterconcentration ratios.

TABLE 2.3 Average metal concentration ratios for the three extrudatesfrom Catalyst A For 30% left and right outer portions and 20% centerPellet Couter(l)/ Couter(l)/ No. Ccenter Couter(r)/CcenterCouter(av)/Ccenter Couter(r) 1 362 539 451 0.67 2 72 80 76 0.91 3 697584 641 1.19 Average 377 401 389 0.92

TABLE 2.4 Average metal concentration ratios for the three extrudatesfrom Catalyst B For 30% left and right outer portions and 30% centerPellet Couter(l)/ Couter(l)/ No. Ccenter Couter(r)/CcenterCouter(av)/Ccenter Couter(r) 1 110 111 111 0.99 2 34 40 37 0.86 3 77 9084 0.85 Average 74 80 77 0.90

3. Hydroalkylation Tests with Rimmed Catalysts

Hydroalkylation tests were performed in a down-flow 0.5″ (12.7 mm)diameter stainless steel fixed bed reactor that was equipped with athree-point thermocouple positioned at the center of the reactor tube.The 4.5″ (114 mm) long catalyst bed was positioned to ensure that threethermocouples (placed 2 inches (5 cm) apart) measured the temperaturesat the inlet, outlet and the center of the catalyst bed. In order toreduce the volumetric heat release and thus to afford more isothermaloperations, the catalyst was diluted with quartz. The diluent alsoenhanced the even distribution of the reactants in the catalyst bed.Neat quartz was used at either side of the catalyst bed. The quartzserved to preheat and evenly distribute the feed at the feed inlet sideand to hold the catalyst bed at the exit side, the latter of which wasat the bottom of the reactor (downflow).

The reactor was encased in a 6 inch (15 cm) long and 1 inch (2.5 cm)diameter brass sleeve that was centered along the catalyst bed toimprove its temperature control. Housed in the brass sleeve were thethree thermocouples positioned at the two ends and the center of thecatalyst bed. The reactor was heated by a three-zone clam-shellelectrical furnace. During steady-state operations, the temperatures ofthe three furnace zones were controlled by utilizing the feedback fromthe three thermocouples in the brass sleeve of the reactor. The catalystbed temperatures at the three thermocouples were typically within 2° C.of the set value. The reported reaction temperatures (T_(rxn)) werecalculated as the weighted average of the three thermocouplemeasurements (T_(inlet), T_(middle), T_(outlet)) by the followingformula:

T _(rxn)=(T _(inlet)+2T _(middle) +T _(outlet))/4.

The catalysts in all experiments nominally contained 0.15 wt % Pdsupported on alumina-bound MCM-49 (alumina/MCM-49 of 20/80 wt/wt). Thecatalyst was received in its calcined form as 1/20″ (1.27 mm) extrudateand was stored in closed plastic bottles. Before charging to thereactor, the catalyst extrudates were broken up along their length andsized to a length/diameter (L/D) ratio of near one (14-20 mesh) toafford the reactor beds with proper hydrodynamics. As mentioned above,the catalyst was also diluted with quartz that on one hand reducedvolumetric catalyst charge and thus volumetric heat release while alsoimproving the desired plug-flow characteristic of the reactant streampassing through the catalyst bed.

In a typical hydroalkylation test, nominally 2 g of 14-20 mesh catalystdiluted with nominally 6 g quartz was charged into the reactor. Themoisture content of the as-loaded catalyst was nominally 12 wt %, thusthe dry catalyst load was typically 1.76 g. After pressure testing, thecatalyst was activated at 50 psig (345 kPa gauge) in flowing purehydrogen. The hydrogen treatment was finished by letting the catalystcool down to near the hydroalkylation temperature (145° C.) whilekeeping the pressure and hydrogen flow rate unchanged. The catalyst thenwas brought on hydroalkylation stream by first increasing the pressureto 165 psig (1138 kPa gauge), then reducing the hydrogen flow rate to 18sccm (standard cubic centimeter) and introducing benzene at 1 mL/minflow rate. This condition was maintained for 1 hour to ensure that thecatalyst bed was properly wetted after which the benzene flow rate wasreduced to 0.096 mL/min corresponding to a nominal 0.7 mol H₂/molbenzene feed composition and 2.5 weight benzene/weight catalyst/h (or2.5/h) weight hourly space velocity (WHSV) on an as-loaded basis (i.e.,catalyst with a nominal moisture content of 12 wt %).

After letting the reactor line out for about 6 hours, the producteffluent was periodically directed to a chilled knock-out vessel held atabout 5° C. and liquid samples were collected then analyzed by a gaschromatograph equipped with a flame-ionization detector (FID). Theresponse factors for the various product components were determinedeither using blends of authentic samples or by using factors publishedin the Journal of Gas Chromatography in February 1967, p 68 by W. A.Dietz. Calibrations were checked by analyzing gravimetrically preparedcalibration blends. Benzene conversion and product selectivity weredetermined from the normalized FID areas by applying the calibrationresponse factors.

Two different rimmed catalyst batches were tested in benzenehydroalkylation. The conditions, benzene conversion, and selectivityresults are listed in Table 3.1.

TABLE 3.1 Benzene conversion and hydroalkylation selectivity with rimmedcatalysts Selectivity (wt %) Benzene cHex + Run Conversion CHB + CHB +No. Catalyst (%) cHex CHB C18 C18 C18 A1 A 35 9 79 10 89 98 A2 A 37 1079 10 89 99 B3 B 36 9 77 13 90 99 0.15 wt % Pd/MCM-49-Al₂O₃ catalyst at145° C., 165 psig (1138 kPa gauge), H₂/benzene molar ratio of 0.7, and2.5/h benzene WHSV Activation conditions: 50 psig hydrogen at a flowrate of 82-84 standard cubic cm/min/g catalyst (1980-2028/h GHSV), rampnominally from ambient temperature to 300° C. at 60° C./hour, hold at300° C. for 2 hours cHex = cyclohexane, CHB = cyclohexylbenzene, C18 =18-carbon fraction benzene WHSV = benzene weight hourly space velocity =g benzene/g catalyst/h

Both catalysts demonstrated surprisingly high alkylation selectivitiesas demonstrated by the combined 86% cyclohexylbenzene anddicyclohexylbenzene selectivity. Catalytic activity was also excellentas shown by the 35-36% benzene conversion. Note that benzene conversionwas limited to less than 100% by the sub-stoichiometric hydrogen feedset for reducing the yield or the cyclohexane by-product.

While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to variations notnecessarily illustrated herein. For this reason, then, reference shouldbe made solely to the appended claims for purposes of determining thetrue scope of the present invention.

Non-limiting embodiments of the present disclosure include:

E1. A process for producing an alkylated aromatic compound, the processcomprising contacting an aromatic starting material and hydrogen with aplurality of catalyst particles under hydroalkylation conditions toproduce an effluent comprising the alkylated aromatic compound, thecatalyst comprising a composite of a solid acid, an inorganic oxidedifferent from the molecular sieve and a hydrogenation metal, whereinthe distribution of the hydrogenation metal in at least 60 wt % of thecatalyst particles is such that:

the average concentration of the hydrogenation metal in the rim portionof a given catalyst particle is Crim;

the average concentration of the hydrogenation metal in the outerportion of a given catalyst particle is Couter; and

the average concentration of the hydrogenation metal in the centerportion of the given catalyst particle is Ccenter; and

at least one of the following conditions is met:

-   -   (i) Crim/Ccenter≧2.0; and    -   (ii) Couter/Ccenter        2.0.

E2. The process of E1, wherein the solid acid comprises a molecularsieve.

E3. The process of E1 or E2, wherein in at least 80 wt % of the catalystparticles, at least one of the following conditions is met:

-   -   (i) Crim/Ccenter≧2.0; and    -   (ii) Couter/Ccenter        2.0.

E4. The process of any of E1 to E3, wherein at least one of thefollowing conditions is met: (i) Crim/Ccenter≧10.0; and (ii)Couter/Ccenter

10.0.

E5. The process of any of E1 to E4, wherein at least 50 wt % of thehydrogenation metal is supported on the inorganic oxide.

E6. The process of E4, wherein at least 75 wt % of the hydrogenationmetal is supported on the inorganic oxide.

E7. The process of any of E1 to E6, wherein the molecular sieve is a MWWtype molecular sieve.

E8. The process of E7, wherein the molecular sieve comprises at leastone of MCM-22, PSH-3, SSZ-25, ERB-1, ITQ-1, ITQ-2, MCM-36, MCM-49, andMCM-56.

E9. The process of any of E1 to E8, wherein the inorganic oxidecomprises an oxide of at least one element of Groups 2, 4, 13, and 14 ofthe Periodic Table of Elements.

E10. The process of E9, wherein the inorganic oxide comprises at leastone of alumina, silica, titania, and zirconia.

E11. The process of any of E1 to E10, wherein the hydrogenation metalcomprises at least one of Pd, Pt, Ru, Ni, Zr, Ru, Ir, Rh, Os and Co.

E12. The process of E11, wherein the hydrogenation metal is Pd, and atleast 60 wt % of Pd is supported on the inorganic oxide support.

E13. The process of any of E1 to E12, wherein the catalyst particles aremade by a catalyst fabrication process comprising:

-   -   (I) forming a mixture comprising the molecular sieve and the        inorganic oxide;    -   (II) forming a pellet from the mixture;    -   (III) depositing a source material of the hydrogenation metal        onto the pellet; and    -   (IV) calcining the pellet after step (III) at a temperature in        the range from 400° C. to 1000° C.

E14. The process of E13, wherein the catalyst fabrication processfurther comprises, after step (IV):

-   -   (V) activating the calcined pellet in the presence of an        atmosphere comprising H₂.

E15. The process of E13 or E14, wherein in step (III), the sourcematerial of the hydrogenation metal comprises PdCl₂, and step (III)comprises impregnating the pellet with an aqueous PdCl₂ dispersionhaving a pH in the range from 0 to 4.

E16. The process of any of E1 to E12, wherein the catalyst particles aremade by a catalyst fabrication process comprising:

-   -   (i) depositing a source material of the hydrogenation metal onto        a plurality of particles of the inorganic oxide;    -   (ii) mixing the particles of the inorganic oxide resulting from        step (i) with a plurality of particles of the molecular sieve;    -   (iii) forming a pellet from the mixture resulting from step        (ii);    -   (iv) calcining the pellet at a temperature in the range from        400° C. to 1000° C.

E17. The process of E16, wherein in step (i), the source material of thehydrogenation metal comprises PdCl₂, and step (i) comprises impregnatingthe particles of the inorganic oxide with an aqueous PdCl₂ dispersionhaving a pH in the range from 0 to 4.

E18. The process of E16 or E17, wherein the catalyst fabrication processfurther comprises, after step (iv):

-   -   (v) activating the calcined pellet in the presence of an        atmosphere comprising H₂.

E19. The process of any of E1 to E12, wherein the catalyst particles aremade by a catalyst fabrication process comprising:

-   -   (a) depositing a source material of the hydrogenation metal onto        a plurality of particles of the inorganic oxide;    -   (b) calcining the particles of the inorganic oxide resulting        from step (a) at a temperature in the range form 400° C. to        1000° C.;    -   (c) mixing the particles of the inorganic oxide resulting from        step (b) with a plurality of particles of the molecular sieve;    -   (d) forming a pellet from the mixture resulting from step (c);        and    -   (e) calcining the pellet at a temperature in the range from        400° C. to 1000° C.

E20. The process of E19, wherein the catalyst fabrication processfurther comprises, after step (e):

-   -   (f) activating the calcined pellet in the presence of an        atmosphere comprising H₂.

E21. The process of any of E1 to E20, wherein the aromatic startingmaterial comprises benzene and/or an alkyl benzene.

E22. The process of E21, wherein the aromatic starting material isbenzene and the alkylated aromatic compound is cyclohexylbenzene.

E23. The process of E22, wherein the molar ratio of hydrogen to benzenein the contacting step is in the range from 0.15:1 to 15:1.

E24. The process of E23, wherein the molar ratio of hydrogen to benzenein the contacting step is in the range from 0.3:1 to 1.0:1.

E25. The process of any of E1 to E24, wherein in the contacting step, acyclic aliphatic compound is produced, and the process furthercomprises:

dehydrogenating at least a portion of the cyclic aliphatic compound toproduce a dehydrogenation stream comprising the aromatic startingmaterial; and

recycling at least part of the dehydrogenation stream to the contactingstep.

E26. The process of E25, wherein:

the aromatic starting material comprises benzene; and the cyclicaliphatic compound is cyclohexane.

E27. A process for making phenol and/or cyclohexanone, the processcomprising:

-   -   (1) producing cyclohexylbenzene according to any of E22 to E26;    -   (2) oxidizing at least a portion of the cyclohexylbenzene to        produce cyclohexylbenzene hydroperoxide; and    -   (3) cleaving at least a portion of the cyclohexylbenzene        hydroperoxide to obtain phenol and cyclohexanone.

E28. A catalyst, the catalyst comprising a composite of a molecularsieve, an inorganic oxide different from the molecular sieve and ahydrogenation metal, wherein the distribution of the hydrogenation metalin at least 60 wt % of the catalyst particles is such that:

-   -   the average concentration of the hydrogenation metal in the rim        portion of a given catalyst particle is Crim;    -   the average concentration of the hydrogenation metal in the        outer portion of a given catalyst particle is Couter; and    -   the average concentration of the hydrogenation metal in the        center portion of the given catalyst particle is Ccenter; and    -   at least one of the following conditions is met:    -   (i) Crim/Ccenter        2.0; and    -   (ii) Couter/Ccenter        2.0.

E29. The catalyst of E28, wherein at least one of the followingconditions is met: (i) Crim/Ccenter≧10.0; and (ii) Couter/Ccenter

10.0.

E30. The catalyst of E28 or E29, wherein the solid acid comprises amolecular sieve.

E31. The catalyst of any of E28 to E30, wherein at least 50 wt % of thehydrogenation metal is supported on the inorganic oxide.

E32. The catalyst of any of E28 to E31, wherein at least 75 wt % of thehydrogenation metal is supported on the inorganic oxide.

E33. The catalyst of any of E28 to E32, wherein the inorganic oxide ispresent in the composite in the form of islets, and the islets aresubstantially uniformly distributed within the composite.

E34. The catalyst of E33, wherein the inorganic oxide islets have anaverage size of at most 40 μm.

E35. The catalyst of any of E28 to E34, wherein the molecular sieve is aMWW type molecular sieve.

E36. The catalyst of E35, wherein the molecular sieve comprises at leastone of MCM-22, PSH-3, SSZ-25, ERB-1, ITQ-1, ITQ-2, MCM-36, MCM-49, andMCM-56.

E37. The catalyst of any of E28 to E36, wherein the inorganic oxidecomprises an oxide of at least one element of Groups 2, 4, 13, and 14 ofthe Periodic Table of Elements.

E38. The catalyst of any of E28 to E37, wherein the inorganic oxidecomprises at least one of alumina, silica, titania, and zirconia.

E39. The catalyst of any of E28 to E38, wherein the hydrogenation metalcomprises at least one of Pd, Pt, Ru, Ni, Zr, Ru, Ir, Rh, Os and Co.

E40. The catalyst of E39, wherein at least 99 wt % of the hydrogenationmetal has an oxidation state of zero.

1. A process for producing an alkylated aromatic compound, the processcomprising contacting an aromatic starting material and hydrogen with aplurality of catalyst particles under hydroalkylation conditions toproduce an effluent comprising the alkylated aromatic compound, thecatalyst comprising a composite of a solid acid, an inorganic oxidedifferent from the solid acid and a hydrogenation metal, wherein thedistribution of the hydrogenation metal in at least 60 wt % of thecatalyst particles is such that: the average concentration of thehydrogenation metal in the rim portion of a given catalyst particle isCrim; the average concentration of the hydrogenation metal in the outerportion of a given catalyst particle is Couter; and the averageconcentration of the hydrogenation metal in the center portion of thegiven catalyst particle is Ccenter; and at least one of the followingconditions is met: (i) Crim/Ccenter≧2.0; and (ii) Couter/Ccenter≧2.0. 2.The process of claim 1, wherein the solid acid comprises a molecularsieve.
 3. The process of claim 1, wherein in at least 80 wt % of thecatalyst particles, at least one of the following conditions is met: (i)Crim/Ccenter≧2.0; and (ii) Couter/Ccenter≧2.0.
 4. The process of claim1, wherein at least one of the following conditions is met: (a)Crim/Ccenter≧10.0; and (b) Couter/Ccenter≧10.0.
 5. The process of claim1, wherein at least 50 wt % of the hydrogenation metal is supported onthe inorganic oxide.
 6. The process of claim 1, wherein the solid acidis a MWW type molecular sieve.
 7. The process of claim 6, wherein thesolid acid comprises at least one of the following molecular sieves:MCM-22, PSH-3, SSZ-25, ERB-1, ITQ-1, ITQ-2, MCM-36, MCM-49, and MCM-56.8. The process of claim 1, wherein the inorganic oxide comprises atleast one of alumina, silica, titania, and zirconia.
 9. The process ofclaim 1, wherein the hydrogenation metal comprises at least one of Pd,Pt, Ru, Ni, Zr, Ru, Ir, Rh, Os and Co.
 10. The process of claim 1,wherein the catalyst particles are made by a catalyst fabricationprocess comprising: (I) forming a mixture comprising the solid acid andthe inorganic oxide; (II) forming a pellet from the mixture; (III)depositing a source material of the hydrogenation metal onto the pellet;and (IV) calcining the pellet after step (III) at a temperature in therange from 400° C. to 1000° C.
 11. The process of claim 10, wherein thesource material of the hydrogenation metal comprises PdCl₂, and thedepositing step comprises impregnating the pellet with an aqueous PdCl₂dispersion having a pH in the range from 0 to
 4. 12. The process ofclaim 10, wherein the catalyst fabrication process further comprises,after step (IV): (V) activating the calcined pellet in the presence ofH₂.
 13. The process of claim 1, wherein the aromatic starting materialis benzene and the alkylated aromatic compound is cyclohexylbenzene. 14.A process for making phenol and/or cyclohexanone, the processcomprising: (1) producing cyclohexylbenzene according to claim 13; (2)oxidizing at least a portion of the cyclohexylbenzene to producecyclohexylbenzene hydroperoxide; and (3) cleaving at least a portion ofthe cyclohexylbenzene hydroperoxide to obtain phenol and cyclohexanone.15. A catalyst, the catalyst comprising a composite of a solid acid, aninorganic oxide different from the solid acid and a hydrogenation metal,wherein the distribution of the hydrogenation metal in at least 60 wt %of the catalyst particles is such that: the average concentration of thehydrogenation metal in the rim portion of a given catalyst particle isCrim; the average concentration of the hydrogenation metal in the outerportion of a given catalyst particle is Couter; and the averageconcentration of the hydrogenation metal in the center portion of thegiven catalyst particle is Ccenter; and at least one of the followingconditions is met: (i) Crim/Ccenter≧2.0; and (ii) Couter/Ccenter≧2.0.16. The catalyst of claim 15, wherein at least one of the followingconditions is met: (a) Crim/Ccenter≧10.0; and (b) Couter/Ccenter≧10.0.17. The catalyst of claim 15, wherein at least 50 wt % of thehydrogenation metal is supported on the inorganic oxide.
 18. Thecatalyst of claim 15, wherein at least 75 wt % of the hydrogenationmetal is supported on the inorganic oxide.
 19. The catalyst of claim 15,wherein the inorganic oxide is present in the composite in the form ofislets, and the islets are substantially uniformly distributed withinthe composite.
 20. The catalyst of claim 19, wherein the inorganic oxideislets have an average size of at most 40 μm.
 21. The catalyst of claim15, wherein the solid acid is a MWW type molecular sieve.
 22. Thecatalyst of claim 21, wherein the solid acid comprises at least one ofthe following molecular sieves: MCM-22, PSH-3, SSZ-25, ERB-1, ITQ-1,ITQ-2, MCM-36, MCM-49, and MCM-56.
 23. The catalyst of claim 15, whereinthe inorganic oxide comprises at least one of alumina, silica, titania,and zirconia.
 24. The catalyst of claim 15, wherein the hydrogenationmetal comprises at least one of Pd, Pt, Ru, Ni, Zr, Ru, Ir, Rh, Os andCo.
 25. The catalyst of claim 24, wherein at least 90 wt % of thehydrogenation metal has an oxidation state of zero.